The present disclosure relates in general to ink-jet recording. In particular, this disclosure relates to ink-jettable overprint compositions and their use in methods for protecting images on a substrate. The overprint compositions of the present disclosure provide a number of advantages to images formed from oil-based ink compositions, such as, for example, image permanence, gloss, thermal stability, lightfastness, smear resistance, and abrasion resistance.
Many liquid-ink compositions, and particularly those used in ink-jet recording, include a colorant, pigment or dye, and a liquid, which is typically an aqueous liquid vehicle, such as water, and/or a low vapor pressure solvent. The ink composition is deposited onto the substrate to form an image in the form of text and/or graphics. Once deposited, the liquid component is removed from the ink composition and the paper to fix the colorant to the substrate by either natural air-drying or by active drying.
Coated substrates and ink-jet recording media for use in ink-jet printers, in particular with non-aqueous pigmented ink compositions, are described, for example, in U.S. Patent Application Publication No. 2005/0078129, the disclosure of which is incorporated herein by reference in its entirety. This publication discloses methods of thermally sealing the overcoat of multilayer media. Ink-jet recording media using overcoat compositions with aqueous ink compositions are also known and are described in Japanese Patent Application Publications JP 2003 053942 A2 and JP 2002 144551 A2, the disclosures of which are incorporated herein by reference in their entirety. Japanese Patent Application Publication JP 2004 230759 A2 also discloses ink-jet recording media for non-aqueous pigmented ink compositions, in which a topcoat layer is composed mainly of inorganic ultra-fine particles with an average particle size of less than 1 micron, and the undercoat layer is composed mainly of an alkaline earth metal salt as a pigment and a binder.
Ink-jet recording media using undercoat compositions, for use with aqueous ink compositions, are described in Japanese Patent Application Publication JP 2004 262232 A2, the disclosure of which is totally incorporated herein by reference. Ink-jet recording media using overcoat compositions, for use with aqueous ink compositions, are described in Japanese Patent Application Publications JP 2003 053942 A2 and JP 2002 144551 A2, the disclosures of which are totally incorporated herein by reference.
U.S. Patent Application Publication No. 2004/0104987, the disclosure of which is incorporated herein by reference in its entirety, describes ink-jet printing systems that include the deposition of fixers and overcoats, in which drops of fixer material and of overcoat material are deposited on previously deposited colored ink drops. In addition, smudge-resistant ink-jet printing systems using overcoat and fixer solutions are also described in U.S. Patent Application Publications Nos. 2004/0056940, 2003/0202039 and 2003/0202026, and in U.S. Pat. Nos. 6,854,823; 6,655,797 and 6,412,935, the disclosures of which are incorporated herein by reference in their entirety. European Patent Application Publication EP 01155866 A2, the disclosure of which is incorporated herein by reference in its entirety, discloses methods of applying fixer fluid overcoats to porous or semi-porous ink-jet printed media.
Dye-stabilized liquid developers and methods for making such developers are described in U.S. Pat. No. 4,476,210, the disclosure of which is incorporated herein by reference in its entirety. This patent discloses liquid developers including marking particles, which include a thermoplastic resin core with an amphipathic block or graft copolymer steric stabilizer that is irreversibly chemically or physically anchored to the thermoplastic resin core and the dye being imbibed in the thermoplastic resin core, dispersed in aliphatic dispersion media. In these developers, the dye is soluble in the thermoplastic resin core and insoluble in the dispersion media.
Methods of ink-jet printing using UV curable undercoats are described, for example, in U.S. Patent Application Publication No. 2003/0067527 and in international patent application publication WO 0030856, the disclosures of which are incorporated herein by reference in their entirety. Ink-jet printers for use with UV curable ink compositions are described in Japanese Patent Application Publication JP 2005 007577 A2, the disclosure of which is incorporated herein by reference in its entirety. Compositions for photo-curable overcoat layers and printed matter are described in Japanese Patent Application Publication JP 2003 292880 A2, the disclosure of which is totally incorporated herein by reference.
Apparatus, methods and wax coatings for improved durability and visual appearance of printed images are described in international patent application publication WO 00184247 A2, the disclosure of which is incorporated herein by reference in its entirety.
Image-receiving layer and overcoat layer compositions, which are cured using an active energy beam, for ink-jet recording are described in European Patent Application Publication EP 01348727 A2, the disclosure of which is incorporated herein by reference in its entirety.
U.S. Patent Application Publication No. 2004/0017409, the disclosure of which is incorporated herein by reference in its entirety, discloses ink-jet recording process and ink-jet recording apparatus in which protective coatings are formed on images by an overcoat device that uses heat transfer sheets.
Japanese Patent Application Publication JP 2004 314350 A2, the disclosure of which is totally incorporated herein by reference, describes methods for ink-jet recording and recorded articles in which a clear ink composition comprising polymer particulates is discharged onto a printed layer, the clear ink composition forms a liquid layer that is then heated to form an overcoat layer.
Ink-jet printers including overcoating printheads, positioned downstream from the ink-jet printheads, that provide coatings that are later hardened over printed images are described in Japanese Patent Application Publication JP 2003 35043 A2, the disclosure of which is incorporated herein by reference in its entirety. Transparent protective overcoats for offset, ink-jet and xerographic images are described in Japanese Patent Application Publication JP 2002 235029 A2, the disclosure of which is incorporated herein by reference in its entirety.
Overcoat layers of water-dispersible, hydrophobic polyester resin are disclosed in U.S. Pat. No. 6,561,644, the disclosure of which is incorporated herein by reference in its entirety. Ink-jet processes for improving image durability and quality by overcoating ink-jet images with layers containing water-dispersible clay particles are described in European Patent Application Publication EP 01393924 A2, the disclosure of which is incorporated herein by reference in its entirety.
Printing methods and apparatus for forming protective layers on printed media by transferring protective agents while avoiding perforated portions of the media are disclosed in U.S. Pat. No. 6,529,225, the disclosure of which is incorporated herein by reference in its entirety.
European Patent Application Publication EP 01524125 A1, the disclosure of which is incorporated herein by reference in its entirety, discloses methods of thermally sealing overcoat layers of multilayer media, in which porous topcoats are heated to close the pores and provide protective layers between the inner ink-receiving layers and the environment.
While a number of compositions and processes, such as those described above, are known for overcoating images produced by ink-jet recording methods, particularly for aqueous ink compositions and photo-curable ink compositions, a need remains for curable overcoat compositions for oil-based ink compositions.
Oil-based liquid ink compositions include a colorant, pigment or dye, and an oil-based liquid. The ink composition is deposited on the substrate to form an image in the form of text and/or graphics. Such oil-based pigmented ink compositions can provide excellent image quality on specially coated papers, such as silica-coated papers. Silica coatings immobilize the colorant on contact, providing sharp images. For example, liquid ink-jet recording oil-based ink compositions, displaying satisfactory pigment dispersibility, are described in U.S. Pat. No. 6,630,153, the disclosure of which is incorporated herein by reference in its entirety.
Oil-based ink compositions for ink-jet printers and methods for their production have been described, for example, in U.S. Patent Application Publications Nos. 2004/0068031 and 2004/0006158, the disclosures of which are incorporated herein by reference in their entirety, and in U.S. Pat. Nos. 6,692,881 and 5,989,325; the disclosures of which are incorporated herein by reference in their entirety.
However, images produced on plain paper using oil-based ink compositions do not generally have good image quality. Oils in the ink compositions spread laterally and vertically through pores in plain, untreated papers, and pigments in the ink compositions spread with the oils. Lateral pigment spread results in images having ragged edges. Vertical pigment spread results in image show-through.
Images formed using oil-based ink compositions, whether printed onto treated or plain paper, can also be degraded by smear and abrasion. Images on plain paper can also have inferior image quality due to the degradation of the color gamut caused by excessive penetration of the ink composition into the paper, which can result in low-gloss, unsaturated colors. This shortfall can also be seen in images formed using oil-based ink compositions on some treated papers. Thus, there exists a need for improved image quality for oil-based ink images.
Attempts have been made to respond to this need. For example, UV curable ink-jet ink compositions have been used in an attempt to overcome the failure of some ink-jet-generated images to withstand heat and sunlight. Typically, such UV curable ink-jet ink compositions include polymerizable monomers, oligomers, or a mixture thereof along with a dye or pigment for color. However, these ink compositions often contain relatively large amounts of toxic solvent or water, as described in U.S. Pat. Nos. 4,978,969 and 5,623,001, respectively, or other toxic components, such as the varnish described in U.S. Pat. No. 5,270,368, or require specific, impractical conditions, such as, the varnish described in U.S. Pat. No. 4,303,924. The disclosures of these U.S. Patents are incorporated herein in their entirety.
In addition, Japanese Patent Application Publication JP 2002-308935 A2 discloses actinic radiation-curable resin overprint compositions for wet-on-wet printing to form glossy printed articles. Similarly, Japanese Patent Application Publication JP 11-092705 A2 discloses an imaging method for a lithographic plate in which a non-aqueous dispersion of resin particles is applied by ink-jet recording over an oil-based ink composition. The disclosures of these Japanese Patent Application Publications are incorporated herein in their entirety.
Thus, there still remains a need for improved compositions and processes, particularly for oil-based pigmented ink compositions and overprint compositions for use with oil-based ink compositions, and methods for use in ink-jet recording to provide glossy, durable images.